Monetizing health co-benefits from transportation strategies that reduce greenhouse gas emissions in the San Francisco Bay Area

BACKGROUND: A health impacts model, which considers physical activity, air pollution, and traffic injuries, estimated significant reductions in the burden of disease and greenhouse gas emissions by replacing some urban car travel with ambitious, but achievable levels of walking and bicycling (active transport) in the San Francisco Bay Area. OBJECTIVES: The objective of this research was to estimate the monetary value of health co-benefits for a modeled scenario that increased per capita median daily active transport time from 4.4 to 22 minutes. METHODS: Electronic bibliographic databases were searched for published research using cost-of-illness and willingness-to-pay methods to monetize costs for diagnostic conditions considered in the health impact model: breast cancer, colon cancer, lung cancer, cardiovascular disease, respiratory disease, dementia, depression, diabetes, traffic injuries, and all-cause mortality. Direct and indirect costs, including productivity losses due to premature death, were considered in cost of illness. Inflation adjusted national estimates of cost of illness (2010 constant dollars) were scaled to the Bay Area population and multiplied by the attributable fraction of disability adjusted life years predicted by the model compared to a business as usual (BAU) scenario. The statistical value of a life was multiplied by the 2,946 premature deaths averted by high levels of active transport compared to BAU. RESULTS: The annual health co-benefits were valued at US $1.4 billion and $21.8 billion (4.4% of the gross regional product) for cost-of-illness and willingness to pay methods, respectively. CONCLUSION: This research demonstrates a large economic value of the health co-benefits of active transport and informs transportation and land use policy, including potential return on investment for pedestrian and bicycling infrastructure. California transportation planning agencies and other stakeholders can incorporate the health impacts model into cost-benefit analyses that are used to prioritize transportation projects.